What is the safest way to convert a CS5.5 file to CS6?

There shouldn't be any information loss when converting from CS5.5 to CS6. You can just open up the CS5.5 file up in CS6 without converting it.

Going back to 5.5 you will have to convert to IDML, which can result in degradation of your document. Can you provide an example of what information you are losing? Screenshots would help.

The fastest way I know to compare files is to print them and throw them on the light table on on top of the other and look for ghosts that shouldn't be there. Acrobat has a compare feature for PDFs, but I've never figured out how to make it work.

The file that lost info, did you open from .indd or from .idml?

Since CS5 I've made it policy to open either .inx or .idml exported from the original version when updating. I never had any troouble with my own files, but other users started reporting strange things (like this) or late stage catastrophic failures with CS3 and CS4 .indd file opened directly in CS5. The export route seemed to solve them almost uninversally, and it just seems like good insurance for the small amount of effort involved.

I've found Acrobat Pro's document compare feature very useful for some jobs, and irritating for others.  One of its modes amounts to light-tabling the two documents, but I usually want a text compare, most recently of a 450-pp. book, where the 250-pp. max. meant I had to do it in two chunks.  Acrobat 9 seems happier with more RAM: I learned not to approach the 250-pp. max on my Vista64 machine with 8 GB, but the package seems more reliable on my Win7 machine with 16 GB.  It often generates quite a few false positives, which take getting used to.  Versions 7 and 8, if I recall correctly, would place the pages side-by-side, which I prefer; version 9 can still be made to do this, I'm note sure about X.

Do these tables have links to external sources?  A new features in CS6 was to keep header rows when relinking tables.

I wonder if this is connected to that feature.

Bob

One way to test would be to kill those links by embedding the tables and then opening the files.

If that works, I think you may have stumbled on a bug.

Bob

Late again I'm afraid, but while looking for another JSX file I bumped into a means for directly comparing ID files, without first generating PDFs for Acrobat Pro to compare: Kasyan Servetsky's script "Compare Two Documents" is described in a 2009 post over at InDesignSecrets.com.  I've never tried it, but it might provide a different answer to the original OP's question:

is there a way to compare either the .INDD/.IDML files or the exported .PDFs without having to go line-by-line on every page?

David

Wow, that script works great! Even though it was written for earlier versions of InDesign it works flawlessly in CS5.

Kasyan even provides 2 sample documents to compare (separate download from the .jsx script)

Did you try to convert troughout the idml export procedure as suggested by Peter?

I'm having issues with some Cs5 documents opening directly into Cs6 and I'd like to know if you have found a solution.